1. Field of the Invention
The present invention relates to a sail system for a sailing craft and, more particularly, to a sail system for a sailboat having a non-rotatable mast.
2. State of the Art
It is well known that the optimum size and shape of a sail for downwind sailing (i.e., sailing before the wind) is substantially different than the optimum sail shape for upward sailing (i.e., sailing against the wind). For downwind sailing, especially in light wind conditions, a craft of a given size can usually carry more sail area than in upwind sailing conditions. Accordingly, for downwind sailing in light wind conditions, many sailing craft utilize a headsail, some types which are referred to as spinnakers, which are attached in front of the mainsail.
One variation to the above-described prior art has been proposed in U.S. Pat. No. 2,107,303 to Ljungstrom. In that patent, the patentee suggests attaching two sails to a single mast so that, when sailing before the wind, the two sails stand out like a parachute sail and, when sailing upwind, the two sails can be doubled against one another to form an ordinary triangular sail. According to the patentee, the mast should be rotatable so that the sails can be rolled about the mast to selectively change the effective sail area depending upon wind conditions. (Sail adjustment of the effective sail area is often referred to as reefing.) Further, the patentee suggests that several generally vertical laths be mounted in the sail; the vertical orientation of the laths is critical to the ability to roll the sail upon the mast for reefing.
Another variation on the prior art attempting to obviate the need for headsails is proposed in U.S. Pat. No. 4,230,060 to McCoy. Similarly to Ljungstrom, the McCoy patent suggests attaching two sails to a mast and providing the mast with a rotation mechanism so that the two sails can be selectively reefed by rotating the mast. In the McCoy patent, the sails are without laths or battens which, apparently, would interfere with rotation of the mast for reefing.
Yet another sailing system utilizing two sails attached to a rotatable mast has been proposed in U.S. Pat. No. 4,367,688 to Godfrey. Godfrey suggests that a sailboat can be provided with twin booms, a doubled triangular sail and a rotatable mast to permit conventional sailing with both booms and sail sections on the same tack or with the booms spread, wind-like, to permit running before the wind or reaching. The rotatable mast suggested by Godfrey permits the sails to be reefed or furled by rotation of the mast. In the Godfrey patent, the sails are also without laths or battens.
In an article appearing in Cruising World in August 1984, pages 98 and 99, there is a report of a sailboat designed by Thomas Godfrey. According to the article, the sail system for the sailboat basically consists of an unstayed spar of tapered elliptical section and a two-ply, wrap-around sail that can be reefed or furled by rotating the spar i.e., the mast). A sailing craft is pictured in the article including the so-called two-ply, wrap-around sail. The pictured sail does not include laths or battens, and that the mast is unstayed.
In U.S. Pat. No. 4,474,126 to King, there is proposed a sailing rig for use on a sailboat comprising a sail formed in the shape of two approximately ellipsoidal portions mounted upon a mast rotatable about its vertical axis. The rotatable mast in the King patent is unstayed but is permanently curved near its top. According to the patentee, the sail system oprates such that, when the sailboat is close-hauled, the sail folds around the mast and when the sailboat runs before the wind, the sail unfolds and opens to fly free of the mast. Further, the patentee suggests that the roach curve can be supported by battens arranged in a suitable configuration. Still further, the patentee suggests that, when the sail is folded around the mast, the foot of the sail at its centerline can be attached to a down-haul line for tensioning the luff of the sail.